New Possibility of Plasma-Magnetic Experiments with Laser
 
H. Yoneda (University of Electro-Communications)

Laser plasmas have a sophisticated variety of parameters in comparison 
to other types of plasmas. For example, laser plasmas have unique 
features of high matter density, high energy density, fast response, 
and high current. In addition, the free surface boundary condition and 
variety of probing technique make it possible to do a large variety of 
experiments. Recently, a new type of study, which combine laser-heated 
plasma with a high magnetic field has begun. One example is the 
generation of a several hundred Megagauss magnetic field with an 
ultra-strong laser pulse. With such a high field, even a plasma near 
solid density can be magnetized and both high and low beta plasmas can 
be produced. Another possibility is precision experiments with high 
repetition-rate ultra-short-pulse lasers. Pump-probe experiments can 
provide details of plasma evolution even with small size scale and very 
rapid time-dependence.   In particular, a strong and rapid 
reduction(10^-3) of electrical conductivity has been found in certain 
high-density plasmas.
This means that we can control the MHD behavior of plasma. Coupled with 
these new trends we can design and achieve first experiments of 
magnetic reconnection in degenerate plasmas, which may tell us 
something about conditions on extreme high-density stars. We can 
perform other totally new categories of experiments, such as rapidly 
heating ferromagnetic materials to plasma temperatures. The kinetics of 
relaxation of spin alignment will provide entirely new information 
about fundamental physical processes that may have astrophysical 
applications.